Different understandings of parliamentarism have characterised the formation of the EU’s political system ever since the establishment of the three European communities in the 1950s. The principle of parliamentarism as the parliament’s right to control the executive formed a part of the ECSC. Due to political controversies alternative understandings of the concept have gained weight in the Union’s political system. Parliamentarism has been advanced in its general meaning, as the power of bodies elected by a popular vote. This conception brings the overall powers of parliamentary bodies to the fore and adds national parliaments to the instruments of parliamentarism at the EU level. A third conception goes back to the classical understanding of parliamentary politics as politics by means of speaking. This paper focuses on the importance of and interaction between different conceptions of parliamentarism in the EU’s political system. It traces conflicts and discusses possible institutional solutions.